Photoresist-coating and photoresist-coating method using the same

ABSTRACT

A photoresist-coating apparatus includes a substrate on which a particle-detecting area and an invalid particle-detecting area are defined, a nozzle discharging photoresist to the substrate and moving along a direction, and a particle-detecting sensor controlling on and off of the nozzle in the particle-detecting area according to presence of particles, wherein in the invalid particle-detecting area, the nozzle operates independently from detection of the particle-detecting sensor.

This application claims the benefit of Korean Patent Application No.2008-0040384, filed on Apr. 30, 2008, which is hereby incorporated byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a photolithography process, and moreparticularly, to a photoresist-coating apparatus and aphotoresist-coating method using the same.

2. Discussion of the Related Art

With the rapid development of information technology, flat panel display(FPD) devices having advantages of thin thicknesses, light weights andlow power consumption, have been developed and have replaced cathode raytubes (CRTs). The FPD devices include liquid crystal display (LCD)devices, plasma display panels (PDPs), electroluminescent display (ELD)devices and field emission display (FED) devices.

An FPD device may be manufactured through a substrate-fabricatingprocess for forming first and second substrates and a cell process forcompleting the FPD device by attaching two substrates with a phosphoricmaterial layer or a polarizing material layer therebetween.

In general, to shorten processes and improve production yields, thesubstrate-fabricating process and the cell process may proceed overlarge-sized substrates, each of which may include a plurality of cellscorresponding to respective display panels and may be referred to as amother glass substrate.

According to this, in the substrate-fabricating process, thin filmdeposition, photolithography and etching steps may be repeatedlyperformed over first and second large-sized substrates to form elementssuch as pixels and thin film transistors in each cell area.

Meanwhile, in the cell process, seal patterns for attaching substratesmay be formed on one of the first and second large-sized substrates, thefirst and second large-sized substrates may be attached with apolarization material layer, for example, therebetween, and the attachedlarge-sized substrates may be cut by each cell to obtain a plurality offlat panel display devices.

Here, the photolithography step includes applying photoresist to asubstrate which includes a thin film thereon, exposing the photoresistto light through a mask which includes predetermined patterns, anddeveloping the light-exposed photoresist to thereby form photoresistpatterns corresponding to the patterns of the mask.

At this time, to apply the photoresist to the substrate, a spin coatingmethod or a slit coating method may be used. In the spin coating method,the photoresist may be dropped on the substrate, and then the substratemay be turned, so that the photoresist may be uniformly applied to thesubstrate. In the slit coating method, the photoresist may be applied tothe substrate by scanning a nozzle which has a slit shape along adirection and discharging the photoresist through the nozzle.

The spin coating method has an advantage that the substrate can beuniformly coated with the photoresist. However, as the size of thesubstrate increases to provide a large-sized display device, thesubstrate gets large and heavy, and thus it is difficult to turn thesubstrate. Accordingly, recently, the slit coating method has beenwidely used.

FIG. 1 is a view of illustrating a slit coating apparatus according tothe related art.

In FIG. 1, a substrate 2 to be processed is disposed on a stage 10, anda slit coating apparatus 20 for applying photoresist to the substrate 2is disposed over the stage 10.

The slit coating apparatus 20 includes a storage unit 30, a supplychannel 34 and a nozzle 36. The storage unit 30 stores and suppliesphotoresist. The supply channel 34 provides a path of the photoresistfrom the storage unit 30 to the nozzle 36. The nozzle 36 discharges thephotoresist to the substrate 2 on the stage 10.

The nozzle 36 may be a slit nozzle having a bar shape across and overthe substrate 10. The nozzle 36 scans and moves along a direction anddischarges the photoresist on a substantially entire surface of thesubstrate 2, thereby coating the substrate 2 with the photoresist.

However, the related art slit coating apparatus 20 has severaldisadvantages.

More particularly, even though particles exist on the substrate 2, therelated art slit coating apparatus 20 does not have any means settlingthe matter, and a photoresist layer may be non-uniformly formed. Tosolve the problem, the slit coating apparatus 20 may include aparticle-detecting sensor (not shown), and the particles on thesubstrate 2 can be detected by the particle-detecting sensor. However,there frequently happens misoperation of the particle-detecting sensor.

As a first cause of the misoperation, the substrate 2, on which aphotoresist layer is formed by the slit coating apparatus 20, may be amother glass substrate and may be cut into a plurality of cell areas,each of which constitutes one display panel, in the following cuttingstep. The particle-detecting sensor may misoperate due to interferencephenomenon from difference between layers in the cell areas and inregions between adjacent cell areas. That is, layers formed in each cellarea differ from layers in the region between adjacent cell areas.

Second, to uniformly apply the photoresist to the substrate 2, thenozzle 36 may accelerate or decelerate at a specific area. At this time,even though there is no particle, the particles-detecting sensor mayperceive that there exist particles due to acceleration or decelerationof the nozzle 36 and may misoperate.

When the particle-detecting sensor misoperates, an operator does notjudge that the particle-detecting sensor misoperates but judges thatthere exist particles on the substrate 2. Accordingly, after stoppingthe slit coating process, the particles on the substrate 2 are checked.Therefore, the efficiency of the process is lowered.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a photoresist-coatingapparatus and photoresist-coating method using the same thatsubstantially obviates one or more of the problems due to limitationsand disadvantages of the related art.

An advantage of the present invention is to provide aphotoresist-coating apparatus and a photoresist-coating method using thesame that exactly detect particles on a substrate and uniformly form aphotoresist layer.

Another advantage of the present invention is to provide aphotoresist-coating apparatus and a photoresist-coating method using thesame that prevent misoperation of a particle-detecting sensor andimprove production yields.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, aphotoresist-coating apparatus includes a substrate on which aparticle-detecting area and an invalid particle-detecting area aredefined, a nozzle discharging photoresist to the substrate and movingalong a direction, and a particle-detecting sensor controlling on andoff of the nozzle in the particle-detecting area according to presenceof particles, wherein in the invalid particle-detecting area, the nozzleoperates independently from detection of the particle-detecting sensor.

In another aspect of the present invention, a photoresist-coating methodincludes discharging photoresist to a substrate by a nozzle moving alonga direction while a particle-detecting sensor detects particles on thesubstrate, wherein a particle-detecting area and an invalidparticle-detecting area are defined on the substrate, and in the invalidparticle-detecting area, discharging photoresist is performedindependently from detection of the particle-detecting sensor.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a view of illustrating a slit coating apparatus according tothe related art;

FIG. 2 is a flow chart showing a photolithography process according toan exemplary embodiment of the present invention;

FIG. 3 is a view of schematically illustrating a slit coating apparatusaccording to an exemplary embodiment of the present invention;

FIG. 4 is a graph of illustrating voltage variation of aparticle-detecting sensor in areas where a nozzle accelerates ordecelerates;

FIG. 5 is a view of schematically illustrating a slit coating apparatusaccording to an exemplary embodiment of the present invention;

FIG. 6A is a graph of illustrating measured time for each step of aphotolithography process using a slit coating method, wherein aparticle-detecting sensor detects particles on a substrate withoutdefining invalid particle-detecting areas. FIG. 6B is a graph ofillustrating measured time for each step of a photolithography processusing a slit coating method, wherein a particle-detecting sensor detectsparticles on a substrate with defining invalid particle-detecting areasaccording to an exemplary embodiment of the present invention; and

FIG. 7 is a view for explaining a slit coating method accordingembodiments to the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 2 is a flow chart showing a photolithography process according toan exemplary embodiment of the present invention.

In FIG. 2, the photolithography process is largely divided into coating,light-exposing, developing and baking steps, and the baking stepincludes pre-baking, soft-baking and hard-baking steps.

At first step st110, pre-baking step is performed. Here, moistureremaining in a thin film deposited on a substrate may be removed, and anadhesive strength between the thin film on the substrate and aphotoresist to be formed later may be improved.

At second step st120, photoresist is applied to the substrate by a slitcoating method. The photoresist may be discharged through a nozzlehaving a slit shape and scanning along a direction over the substrate,and the photoresist may be uniformly applied to the substrate to form aphotoresist layer.

At third step st130, soft-baking is performed. To vaporize volatilecomponents such as solvent of the photoresist, the soft-baking step maybe carried out in an in-line system using a substrate-heating apparatussuch as a hot plate under the atmosphere condition.

Next, at fourth step st140, aligning and light-exposing are performed.The substrate passing through the vaporizing step may be aligned with amask, and the substrate may be exposed to light through the mask totransfer patterns of the mask to the substrate. Here, the photoresistlayer may include a first portion, which is exposed to the light and ischemically changed, and a second portion, which is not exposed to thelight.

At fifth step st150, the first portion or the second portion of thephotoresist layer is selectively removed by a developer depending on thetype of the photoresist layer, and photoresist patterns corresponding tothe patterns of the mask are formed.

At sixth step st160, hard-baking is performed. The substrate may beheated so that the volatile elements in the photoresist patterns arecompletely removed. Accordingly, the photoresist patterns become denseand uniform.

According to the first to sixth steps st110 to st160, the thin film isselectively exposed by the photoresist patterns.

At seventh step st170, the exposed portions of the thin film areremoved, and then the remaining photoresist patterns are removed.Therefore, intended patterns are obtained.

In the second step st120, a slit coating apparatus according toembodiments of the present invention may be used for applying thephotoresist to the substrate that accurately detects particles on thesubstrate and enables the photoresist layer to be uniformly formed onthe substrate.

FIG. 3 is a view of schematically illustrating a slit coating apparatusaccording to an embodiment of the present invention and also shows asubstrate on which a photoresist layer is formed by the slit coatingapparatus.

In FIG. 3, a substrate 102 to be processed is disposed on a stage 210,and a slit coating apparatus 220 for applying photoresist to thesubstrate 102 is disposed over the stage 210.

The slit coating apparatus 220 includes a storage unit 230, a supplychannel 234, a nozzle 236, a thickness-measuring sensor (not shown) anda particle-detecting sensor 240. The storage unit 230 includes storesand supplies photoresist. The supply channel 234 provides a path of thephotoresist from the storage unit 230 to the nozzle 236. The nozzle 236discharges the photoresist to the substrate 102 on the stage 210. Thethickness-measuring sensor measures the thickness of the substrate 102.The particle-detecting sensor 240 detects particles on the substrate102.

The storage unit 230 may include at least one canister (not shown) forstoring the photoresist and a pressing means (not shown) such as a pumpfor providing the photoresist to the supply channel 234. The supplychannel 234 may include a connecting pipe.

The storage unit 230 supplies the nozzle 236 with the photoresistthrough the supply channel 234 and applies pressure to the photoresistsuch that the photoresist is discharged to the outside.

The nozzle 236 may be a slit nozzle having a bar shape across and overthe substrate 102 with a length corresponding to the substrate 102. Thenozzle 236 may include a discharging hole (not shown) having a slitshape at a lower surface of the nozzle 236 facing the substrate 102. Auniform amount of photoresist may be discharged to the substrate 102through the discharging hole.

The nozzle 236 scans and moves from one side to the other side of thesubstrate 102 and discharges the photoresist to a substantially entiresurface of the substrate 102 to coat the substrate 102 with thephotoresist while both ends of the nozzle 236 are supported by a coupleof nozzle-transporting units 251 and 253.

Alternatively, the photoresist may be applied to the substrate 102 bysliding the substrate 102 on the stage 210 while the nozzle 236 isfixed.

The thickness-measuring sensor (not shown) measures the thickness of thesubstrate 102 to be coated with the photoresist and controls a distancebetween the substrate 102 and the nozzle 236 according to the measuredthickness of the substrate 102.

At this time, the distance between the substrate 102 and the nozzle 236may be minutely adjusted considering the viscosity and the amount of thephotoresist to be applied. Since the photoresist is dried right afterbeing applied to the substrate 102, the viscosity of the appliedphotoresist may be changed as time passes. Therefore, the distancebetween the nozzle 236 and the substrate 102 should be minutelycontrolled.

The nozzle 236 waits while the thickness of the substrate 102 ismeasured by the thickness-measuring sensor, and after measuring thethickness of the substrate 102, the nozzle 236 scans and moves.

In addition, a light-emitting portion 241 and a light-receiving portion243 of the particle-detecting sensor 240 are installed in front of thecouple of nozzle-transporting units 251 and 253 supporting both ends ofthe nozzle 236, respectively. Light 245 emitted from the light-emittingportion 241 is received by the light-receiving portion 243, and thus theamount of light is determined. The light 245 may be a laser beam.

At this time, if there is no particle between the light-emitting portion241 and the light-receiving portion 243, all the light 245 emitted fromthe light-emitting portion 241 are incident on the light-receivingportion 243. On the other hand, if there exist particles between thelight-emitting portion 241 and the light-receiving portion 243, some ofthe light 245 emitted from the light-emitting portion 241 are screenedby the particles, and only the others of the light 245 are incident onthe light-receiving portion 243. Accordingly, the amount of lightreceived by the light-receiving portion 243 is reduced as compared witha normal state, and in this case, it is determined that there existparticles between the light-emitting portion 241 and the light-receivingportion 243.

Like this, if the particles on the substrate 102 are detected by theparticle-detecting sensor 240, the slit-coating apparatus 220 stops theslit-coating process by stopping the nozzle 236 from discharging thephotoresist and moving and by forcing the nozzle to wait. Then, afterthe particles detected on the substrate 102 are checked, the particlesare removed or the substrate 102 is disused.

At this time, a particle-detecting area A on the substrate 102 issubdivided.

More particularly, to uniformly apply the photoresist to the substrate102, the nozzle 236 may accelerate or decelerate in a specific area. Atthis time, the particle-detecting sensor 240 may perceive a minutevibration because of the acceleration or deceleration of the nozzle 236.Accordingly, the amount of light received by the light-receiving portion243 may change, and the particle-detecting sensor 240 may recognize thatthere exist particles in areas where the nozzle 236 accelerates ordecelerates. Accordingly, the areas where the nozzle 236 accelerates ordecelerates are defined as examples of invalid particle-detecting areasB, and the particle-detecting area A is subdivided.

In the invalid particle-detecting areas B, sensing of theparticle-detecting sensor 240 is disregarded, and process time isshortened in comparison to the related art. Thus, stops of theslit-coating apparatus 220 due to misoperation of the particle-detectingsensor 240 are decreased.

FIG. 4 is a graph of illustrating voltage variation of aparticle-detecting sensor in areas where a nozzle accelerates ordecelerates.

In FIG. 4, the nozzle 236 accelerates or decelerates in first and secondareas x1 and x2, and at these times, the voltage of theparticle-detecting sensor 240 is changed. In general, the voltagevariation of the particle-detecting sensor 240 means that theparticle-detecting sensor 240 perceives particles on the substrate 102.

However, the first and second areas x1 and x2 in which the nozzle 236accelerates or decelerates may be areas where the nozzle 236 startsmoving at one side of the substrate 102 to discharge the photoresist onthe substrate 102 on the stage 210 and where the nozzle 236 stops movingat the other side of the substrate 102 after discharging the photoresiston a substantially entire surface of the substrate 102. Or, the firstand second areas x1 and x2 may be areas where the nozzle 236 deceleratesso that the thickness of the substrate 102 is measured by thethickness-measuring sensor (not shown) and where the nozzle 236accelerates to move again after measuring the thickness of the substrate102 by the thickness-measuring sensor.

That is, the particle-detecting sensor 240 does not detect realparticles on the substrate 102, but the particle-detecting sensor 240misoperates as if the particles are detected due to minute vibrationfrom the acceleration or deceleration of the nozzle 236.

Accordingly, even though the particle-detecting sensor 240 detectsparticles in the first and second areas x1 and x2 of the graph while thephotoresist is uniformly applied to the substrate 102 by theslit-coating apparatus 220, the perception of the particle-detectingsensor 240 is disregarded, and the slit-coating process is normallyperformed. Here, the first and second areas x1 and x2 become the invalidparticle-detecting areas B.

In the meantime, the particle-detecting sensor 240 may include a controlunit (not shown) such that the particle-detecting sensor 240 ignores theperception in the invalid particle-detecting areas B and theslit-coating apparatus 220 normally performs the process. The controlunit may be a computer, and the areas where the nozzle 236 acceleratesor decelerates are defined in the control unit. The particle-detectingsensor 240 may further include a monitor device (not shown) that showsthe result of perception of the particle-detecting sensor 240 in theinvalid particle-detecting areas B.

Here, the substrate 102 may be a substrate for a liquid crystal displaydevice to be processed by the slit-coating apparatus 220. To reduce theprocess and increase the production yields, the substrate 102 may be amother glass substrate including a plurality of cell areas 101, each ofwhich corresponds to a display device.

As shown in FIG. 5, in the control unit, areas where there may occur aninterference phenomenon due to difference between layers in the cellareas 101 and in regions between adjacent cell areas 101 on thesubstrate 102 are also defined as the invalid particle-detecting areas Bin addition to the areas where the nozzle 236 accelerates ordecelerates. Accordingly, the control unit enables theparticle-detecting sensor 240 to ignore the perception in the invalidparticle-detecting areas B.

As stated above, by defining the invalid particle-detecting areas B anddisregarding the perception of the particle-detecting sensor 240 in theareas B, process time is shortened in comparison to the related art, andthis is why it is decreased that the slit-coating apparatus 220 stopsdue to misoperation of the particle-detecting sensor 240.

That is, even though there is no particle, the particle-detecting sensor240 may misoperate as if the particles are detected due to minutevibration from the acceleration or deceleration of the nozzle 236 andthe interference phenomenon by difference between layers in the cellareas 101 and in regions between adjacent cell areas 101 on thesubstrate 102. At this time, the operator may not judge that theparticle-detecting sensor misoperates but may judge that there existparticles on the substrate 102. To check the particles on the substrate102, the slit coating process may be stopped. Therefore, the efficiencyof the process may be lowered. However, in the embodiments of thepresent invention, problems due to misoperation of theparticle-detecting sensor 240 are prevented.

FIG. 6A is a graph of illustrating measured time for each step of aphotolithography process using a slit coating method, wherein aparticle-detecting sensor detects particles on a substrate withoutdefining invalid particle-detecting areas. FIG. 6B is a graph ofillustrating measured time for each step of a photolithography processusing a slit coating method, wherein a particle-detecting sensor detectsparticles on a substrate with defining invalid particle-detecting areasaccording to an exemplary embodiment of the present invention.

In FIG. 6A, an average time for each step of the photolithographyprocess is 52.5 seconds. In FIG. 6B, an average time for each step ofthe photolithography process according to the present invention is 51.9seconds, which is reduced by 0.6 seconds as compared with the averagetime for each step of the photolithography process according to therelated art in which the invalid particle-detecting areas are notdefined.

This is because the process is less often stopped than the related art,in which the whole slit coating process is stopped when theparticle-detecting sensor 240 operates as it detects particles due tominute vibration by the acceleration or deceleration of the nozzle 236or due to difference between layers in the cell areas and in regionsbetween adjacent cell areas on the substrate 102 even if there is noparticle in specific areas. Accordingly, process speed can be improved.

Meanwhile, the time measured at each step of the photolithographyprocess in FIGS. 6A and 6B is process time required when thephotolithography process is completely performed over one substrate 102.To reduce process time and costs, the photolithography process may becarried out with an in-line system in which the substrate 102 isprocessed while being transferred. In embodiments of the presentinvention, the time of the photolithography process over the substrate102 is reduced by 0.6 seconds, and time of total photolithographyprocesses can be considerably decreased. Accordingly, the productionyields of the photolithography process can be rather increased.

FIG. 7 is a view for explaining a slit coating method according anembodiment of to the present invention.

In FIG. 7, a substrate 102 to be coated with photoresist is disposed ona stage 210, and a nozzle 236 of a slit coating apparatus 220 isdisposed over and across the substrate 102.

A thickness of one side of the substrate 102 is measured by athickness-measuring sensor (not shown) of the slit coating apparatus220, and then the nozzle 236 scans and moves from one side to the otherside of the substrate 102 by a couple of nozzle-transporting units 251and 253 at a regular speed to thereby discharge and apply photoresist toa substantially entire surface of the substrate 102.

At this time, light 245 such as a laser beam is emitted from alight-emitting portion 241 of a particle-detecting sensor 240, which isinstalled at one of the moving nozzle-transporting units 251 and 253,and is received by the light-receiving portion 243 of theparticle-detecting sensor 240, which is installed at the other of thenozzle-transporting units 251 and 253. According to this, the amount oflight is determined, and particles on the substrate 102 can be detected.

In the meantime, when the nozzle 236 scans and moves after the thicknessof the substrate 102 is measured by the thickness-measuring sensor (notshown), even though the particle-detecting sensor 240 operates as itdetects particles due to minute vibrations from acceleration of thenozzle 236, the nozzle 236 continuously scans and moves over thesubstrate 102.

Additionally, even though the particle-detecting sensor 240 operates asit detects particles due to minute vibrations from deceleration of thenozzle 236 that reaches the other side of the substrate 102, the nozzle236 disregards this and completes the coating process over the substrate102.

That is, the areas where the nozzle 236 accelerates or decelerates aredefined as invalid particle-detecting areas B of FIG. 3, and it isdisregarded that the particle-detecting sensor 240 detects particles inthe areas.

Meanwhile, in addition to the areas where the nozzle 236 accelerates ordecelerates, areas where there occurs an interference phenomenon due todifference between layers in cell areas and in regions between adjacentcell areas 101 on the substrate 102 may be also defined as the invalidparticle-detecting areas B of FIG. 3.

As stated above, by defining the invalid particle-detecting areas B ofFIG. 3, perception of the particle-detecting sensor 240 is disregardedin the invalid particle-detecting areas B of FIG. 3, and process timecan be shortened as compared with the related art. Accordingly, problemsdue to misoperation of the particle-detecting sensor 240 can beprevented. Moreover, process efficiency can be improved.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A photoresist-coating apparatus, comprising: asubstrate on which a particle-detecting area and an invalidparticle-detecting area are defined; a nozzle discharging photoresist tothe substrate and moving along a direction; and a particle-detectingsensor controlling on and off of the nozzle in the particle-detectingarea according to presence of particles, wherein in the invalidparticle-detecting area, the nozzle operates independently fromdetection of the particle-detecting sensor, wherein the nozzleaccelerates or decelerates in the invalid particle-detecting area. 2.The apparatus according to claim 1, wherein the substrate includes twocell areas, each of which corresponds to a display panel, and theinvalid particle-detecting area is between one of the cell areas and aregion between the cell areas.
 3. The apparatus according to claim 1,further comprising a couple of nozzle-transporting units supporting bothends of the nozzle, respectively.
 4. The apparatus according to claim 1,wherein the particle-detecting sensor includes a light-emitting portionand a light-receiving portion.
 5. The apparatus according to claim 1,wherein the nozzle is a slit nozzle having a bar shape.